Ballistic-resistant panel including high modulus ultra high molecular weight polyethylene tape

ABSTRACT

A ballistic-resistant panel in which the entire panel or a strike-face portion thereof is formed of a plurality of sheets of high modulus high molecular weight polyethylene tape. The sheets of high modulus polyethylene tape can be in the form of cross-plied laminated layers of tape strips or a woven fabric of tape strips. The strips of UHMWPE tape include a width of at least one inch and a modulus of greater than 1400 grams per denier. The ballistic-resistant panel may include a backing layer of conventional high modulus fibers embedded in resin. A wide variety of adhesives were found acceptable for bonding the cross-plied layers of high modulus polyethylene tape together for forming the ballistic-resistant panels of the present invention.

This application is a Continuation-In-Part of U.S. patent applicationSer. No. 11/821,659, filed on Jun. 25, 2007 and entitled “Non-FibrousHigh Modulus Ultra High Molecular Weight Polyethylene Tape for BallisticApplications” and is a Continuation-In-Part of U.S. patent applicationSer. No. 11/787,094, filed on Apr. 13, 2007 and entitled “Wide UltraHigh Molecular Weight Polyethylene Sheet and Method of Manufacture”, ofwhich the entire contents of said applications are incorporated hereinin their entirety by reference thereto.

FIELD OF THE INVENTION

The present invention relates to survivability enhancement and moreparticularly to a ballistic laminate constructed of a plurality oflayers of non-fibrous high modulus ultra high molecular weightpolyethylene.

BACKGROUND OF THE INVENTION

Survivability enhancement is a well-known objective for armored vehiclesor fixed or mobile armored structures in a combat or other high threatenvironment. If a high-energy projectile strikes a vehicle, thesurvivability of the occupants and the vehicle can be compromised by therelease of spall, which is a spray of high velocity metallic or ceramicdebris into the vehicle's interior. Vehicles, ships, aircraft, orstructures in a high threat environment are therefore frequentlyequipped with a spall liner, which is designed to suppress the spallgenerated when a projectile penetrates the vehicle's interior.

Spall liners are typically comprised of a compressed panel. Thecompressed panel usually includes a plurality of layers of high modulus,high tensile strength fabric bonded together by a resinous adhesive. Ifa projectile penetrates the armor of a vehicle, the spall liner absorbsthe force of the projectile, with each separate layer delaminating andabsorbing some portion of the force of the projectile and therebydissipating the energy of the projectile as it advances through thespall liner.

Although many different spall liners have been proposed, furtherenhancements in spall suppression are highly desirable for increasingsurvivability of armored vehicles and structures.

SUMMARY OF THE INVENTION

The invention is a ballistic-resistant panel formed of a plurality ofsheets of high modulus high molecular weight polyethylene tape. Thesheets of high modulus polyethylene tape include tape strips bondedtogether at their edges by heat and pressure or by thermoplasticadhesive combined with heat and pressure. The strips of UHMWPE (ultrahigh molecular weight polyethylene) tape include a width of at least oneinch and a modulus of greater than 1400 grams per denier. Theballistic-resistant panel may include a backing layer of conventionalhigh modulus fibers embedded in resin. A wide variety of adhesives werefound acceptable for bonding the sheets of high modulus polyethylenetape together for forming the ballistic-resistant panels of the presentinvention.

OBJECTS AND ADVANTAGES

The ballistic-resistant panel formed of UHMWPE (ultra high molecularweight polyethylene) Tensylon tape of the present invention includesseveral advantages over the prior art, including:

-   -   (1) The ballistic resistance is improved over ballistic panels        formed entirely of conventional ballistic fibers.    -   (2) The UHMWPE Tensylon tape of the present invention can be        produced at a substantially lower price than conventional        ballistic fibers. Significant cost savings are therefore        obtained by replacing a portion of the conventional high modulus        component with the high modulus UHMWPE tape of the present        invention.    -   (3) Forming the ballistic-resistant panel or the strike-face        portion of monolithic UHMWPE tape reduces or eliminates joints        or seams, thereby improving the ballistic resistance of the        ballistic laminate.    -   (4) Forming the strike-face portion of monolithic UHMWPE tape        provides structural support to the laminate and reduces        delamination after a ballistic event.    -   (5) The UHMWPE tape of the present invention may be formed into        sheets or layers by weaving the wide tapes into a woven        structure such as a simple basket weave or by simply butting        together the strips of tape edge to edge, or by overlapping the        edges slightly, and then pressing with pressure, heat and        pressure, or by coating with adhesive and pressing. This is        vastly simpler and cheaper than forming a sheet or layer from        fibers, which requires many more individual ends or packages and        lamination with an adhesive or processing by weaving, knitting,        or cross-stitching.    -   (6) The amount of adhesive required to mold a ballistic laminate        with a strike-face according to the present invention is        significantly lower than that required for a ballistic laminate        formed of conventional ballistic fibers. The smooth surface area        of the high modulus tape used in the strike-face portion of the        ballistic-resistant panel enables a lower adhesive to UHMWPE        ratio than is available with ballistics panels formed from        conventional UHMWPE. The effectiveness of conventional        ballistic-resistant panels is generally negatively affected by        the higher adhesive ratios, as the adhesive portion adds weight        to the laminate but does not contribute to the ballistic        resistance unless the adhesive is specifically designed to        produce controlled delamination.

These and other objects and advantages of the present invention will bebetter understood by reading the following description along withreference to the drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a production process forlaminating UHMWPE tape with adhesive in order to produce layers forforming a ballistic laminate according to the present invention.

FIG. 2 is a schematic representation of a second production process forlaminating UHMWPE tape with adhesive for the production of a ballisticlaminate according to the present invention.

FIG. 3 is a schematic representation in perspective view of two sheetsor layers of adhesive-coated unidirectional non-fibrous UHMWPE tapeprior to being fused together with heat and pressure to form across-plied laminate for use in the construction of a ballistic laminateaccording to the present invention.

FIG. 4 is a schematic representation as viewed from the side of twosheets of unidirectional non-fibrous UHMWPE tape prior to being fusedtogether with heat and pressure to form a cross-plied laminate.

FIG. 5 is an illustration depicting the forming of a ballistic-resistantpanel with cross-plied sheets of adhesive-coated Tensylon andcross-plied sheets of conventional high modulus fibers embedded inresin.

FIG. 6 is a graph depicting ballistic resistance at various moldingtemperatures and at two separate molding pressures for 2.0 psf panelshaving 100% Tensylon tape as the high modulus component.

Table of Nomenclature

The following is a listing of part numbers used in the drawings alongwith a brief description:

Part Number Description 20 laminator/fuser 22 unwind shaft 24 Tensylontape 26 second unwind shaft 28 adhesive 30 third unwind shaft 32 fourthunwind shaft 34 silicone release paper 36 nip rolls 38 adhesive coatedTensylon web 40 fusing oven 42 chilled platen 44 adhesive coatedunidirectional tape 50 laminator/fuser 52 adhesive coated release roll54 release liner 60 top sheet of adhesive-coated unitape 62 bottom sheetof adhesive-coated unitape 64 strip of Tensylon unidirectional tape 66joint areas 68 adhesive layer 70 cross-plied sheet of adhesive-coatedTensylon 72 cross-plied sheet of adhesive-coated Tensylon 74 cross-pliedsheet of convention fibers in resin 76 cross-plied sheet of conventionfibers in resin

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to ballistic laminates having a pluralityof layers of high modulus material, either all or some portion of whichlayers are constructed of non-fibrous, high modulus, ultra highmolecular weight polyethylene tape of the type described in U.S. patentapplication Ser. No. 11/787,094, filed on Apr. 13, 2007, the contents ofwhich are incorporated herein in their entirety by reference thereto.The non-fibrous, high modulus, UHMWPE tape is produced by Tensylon HighPerformance Materials, Inc. of Monroe, N.C., and sold under the nameTENSYLON®. As used in this application, the term “high modulus” refersto materials having a modulus greater than 1,000 grams per denier (gpd).

In order to form an improved strike-face for a ballistic-resistant panelaccording to the present invention, adhesive was applied to one side ofa plurality of webs of unidirectional UHMWPE tape. The webs ofadhesive-coated unitape were bonded into a unidirectional or unitapesheet, sheeted, and then cross-plied with additional sheets ofadhesive-coated unitape. The cross-plied sheets were molded by heat andpressure into a ballistic laminate. Several conventional adhesives weretested for their effectiveness in forming a ballistic laminate. The testprocedure included the following steps:

-   -   (1) Comparing various adhesives for bonding UHMWPE tape for the        purpose of forming unidirectional material for use in        bidirectional cross ply;    -   (2) Evaluating unidirectional tape lamination capability and        consolidation capability;    -   (3) Forming each adhesive variant into a nominal 2.0 pounds per        square foot (pst) test panel at 150 psi and into a second 2.0        psf panel at 3000 psi; and    -   (4) Testing the resultant test panels for ballistic performance.

In order to test the effectiveness of TENSYLON® non-fibrous, highmodulus UHMWPE tape as a high modulus component in ballistic-resistantpanels, adhesive was applied to one side of Tensylon 19,000 denier tape,hereinafter “Tensylon tape”. The 19,000 denier Tensylon tape includednominal dimensions of 1.62 inches in width, 0.0025 inch in thickness,and a tensile modulus of at least 1,400 grams per denier (gpd). Some ofthe adhesives were in the form of adhesive scrims, which were laminatedto one side of the Tensylon tape, and others were resinous adhesivedispersed in a solvent, which was coated on a release film and thentransferred to one side of the Tensylon tape. Preferably, the Tensylontape has viscosity-average molecular weight of at least 2,000,000, awidth of at least 1.0 inch, a thickness of between 0.0015 and 0.004inch, a with to thickness ration of at least 400:1, a denier of 6,000 orgreater, and a modulus of greater than 1,400 grams per denier.

With reference to FIG. 1, there is shown a laminator/fuser 20 forlaminating adhesive scrims to the Tensylon tape. The laminator/fuser 20included an unwind shaft 22 with eight rolls of 1.62-inch wide Tensylontape 24 assembled thereon. Each roll included independent brake tensioncontrols. A second unwind shaft 26 contained a roll of adhesive 28. Athird unwind shaft 30 and forth unwind shaft 32 contained rolls ofsilicone release paper 34. The Tensylon tape 24, adhesive 28, andsilicone release paper 34 were laminated together at nip rolls 36thereby forming adhesive coated Tensylon web 38 sandwiched between thetwo silicone release liners 34. The silicone release liners 34 preventedthe adhesive coated Tensylon web 38 from sticking to any rollers in theoven during fusing. The adhesive coated Tensylon web 38 was thenconveyed through a fusing oven 40 to cure the thermoplastic adhesive. Achilled platen 42 cooled the Tensylon/adhesive laminate 38 as it exitedthe fusing oven 40. After cooling, the release liners 34 were removedfrom the Tensylon/adhesive laminated web 38 thereby formed anadhesive-coated roll of unidirectional Tensylon 44 at a nominal width of13.0 inches. The laminator/fuser operated at a line speed of 10 to 20feet per minute and with fusing oven 40 temperatures between 230° F. and260° F.

For those adhesives in the form of a resin suspended in a solvent, theresin was applied to one side of a silicone release sheet. Withreference to FIG. 2, there is shown a laminator/fuser 50 in which theadhesive-coated silicone release roll 52 was mounted on an unwind shaft30 with Tensylon tape 24 on unwind shaft 22. The adhesive-coatedsilicone release web 52 was then nipped against the 1.62-inch wideTensylon webs that were butt-jointed together at the nip 36. At the nipthe adhesive was transferred to the Tensylon web and the eight 1.62-inchTensylon webs were fused into one sheet as has been described in U.S.patent application Ser. No. 11/787,094, filed Apr. 13, 2007, thecontents of which are incorporated herein in their entirety by referencethereto. The adhesive-coated Tensylon 38 was then conveyed through theremainder of the laminator/fuser 50 and the release liner 54 removedfrom the 13.0-inch nominal width Tensylon/adhesive-coated web 38.

The specific adhesives tested and significant measured properties arepresented in Table 1 below:

TABLE 1 Adhesives Tested for effectiveness in bonding Tensylon tape intoa ballistic laminate: Adhesive Chemical Melt Temperatures Measured CoatCode Composition (degrees C.) Weight (gsm) A1 Polyamide 100-115  6.2 B1Polyolefin 93-105 6.0 C1 Ethylene Vinyl 98-112 4.7 Acetate Copolymer D1Polyurethane 70-100 16.7  E1 Ethylene Acrylic 88-105 N/A Acid CopolymerF1 Polystyrene Isoprene N/A 6.0 Copolymer G1 Polyamide N/A 5.0 H1Polyurethane N/A 5.0

The adhesives tested included Polyethylene-PO4401 (A1),Polyethylene-PO4605 (B1), Polyethylene-DO184B (C1), Polyurethane-DO187H(D1), and Polyethylene-DO188Q (E1), which are all available fromSpunfab, Ltd. of Cayahoga Falls, Ohio; Kraton D1161P (F1), which isavailable from Kraton Polymers U.S., LLC of Houston, Tex.; Macromelt6900 (G1), which is available from Henkel Adhesives of Elgin, Ill.; andNoveon-Estane 5703 (H1), which is available from Lubrizol AdvancedMaterials, Inc. of Cleveland, Ohio. Adhesives A1 through E1 were appliedto the Tensylon tape by the laminator/fuser 20 depicted in FIG. 1.Adhesives F1 through H1, which were dispersed in solvents, were coatedon a release film and then transferred to one side of the Tensylon tape.

The adhesive-coated unidirectional Tensylon tape, commonly termed“unitape” and consisting of eight strips of UHMWPE tape fused at theiredges, was then cut into 12-inch by 12-inch sheets. FIGS. 3 and 4 depicttwo sheets 60 and 62 of adhesive-coated unitape consisting of strips ofTensylon UHMWPE tape 64 fused at joint areas 66. The joint areas 66 aredepicted for clarity in describing the direction of orientation of theUHMWPE tape in FIG. 3, it should be understood that the UHMWPE tapestrips 64 are rendered substantially transparent when bonded asdescribed herein therefore making the joint areas 66 appear homogenouswith the sheet. The bonding of non-fibrous, high modulus, ultra highmolecular weight polyethylene Tensylon tape is described in detail inU.S. patent application Ser. No. 11/787,094, filed on Apr. 13, 2007,which has been incorporated herein by reference. The top sheet 60 ofadhesive-coated unitape is oriented at 90° with respect to the bottomsheet 62. An adhesive layer 68, shown as a transparent layer of adhesivein FIGS. 3 and 4, is bonded to each sheet 60, 62 in the manner describedabove. As the adhesive is thermoplastic, the two sheets 60, 62 ofadhesive-coated unitape are pressed together with heat and pressurewhich causes the two sheets to bond together into a cross-plied sheet ofTensylon UHMWPE with the bonded sheets cross-plied in the 0° and 90°direction.

To form a ballistic-resistant panel, cross-plied sheets ofadhesive-coated Tensylon were stacked until a stack of cross-pliedTensylon of approximately 2.0 psf (pounds per square foot) was obtained.Several of the nominal 2.0 psf stacks were pressed at a pressure of 150psi and several at a pressure of 3,000 psi. The press cycle included 30minutes at a temperature of 250° F. to 260° F. and cooling under fullpressure to below 120° F. before release thereby formingballistic-resistant panels of nominally 2.0 psf areal density.

With reference to FIG. 5, a simplified illustration depicts the formingof the preferred embodiment of a ballistic-resistant panel withcross-plied sheets or laminates of adhesive-coated Tensylon 70 and 72and cross-plied sheets of conventional high modulus fibers embedded inresin 74 and 76. The cross-plied sheets of adhesive-coated Tensylon 70and 72 are stacked on top of stacked cross-plied sheets of conventionalhigh modulus fibers 74 and 76 and pressure and heat are applied to bondthe sheets into a ballistic-resistant panel. As an example, to form a2.0 psf ballistic-resistant panel having a 50/50 ratio by weight ofTensylon and conventional fiber, a plurality of sheets of cross-pliedconventional fibers embedded in resin are laid down until a weight ofapproximately 2.0 psf is obtained. Cross-plied sheets of adhesive-coatedTensylon are then stacked on top of the cross-plied sheets ofconventional high modulus fibers until a total weight of approximately2.0 psf was obtained. Heat and pressure are then applied to fuse thecross-plied layers of Tensylon and conventional fibers into aballistic-resistant panel.

The ballistic-resistant panels were then tested for ballisticresistance. Projectiles of 0.30 caliber FSP (Fragment SimulatedProjectile) per MIL-P-46593A were fired at the 2.0 psf test panels toobtain ballistics properties of the panels bonded with the variousadhesives. The velocities in fps (feet per second) at which 50% of theprojectiles failed to penetrate the target (V₅₀) were determined perMIL-STD-662F. Data for the resultant ballistic-resistant panels formedat 150 psi are shown in Table 2 and data for the resultantballistic-resistant panels formed at 3,000 psi are shown in Table 3below:

TABLE 2 Data Results for Ballistic-resistant panels of UHMWPE tapeformed with various adhesives at Molding Pressure 150 psi and BallisticTest Results: Adhe- Average Adhesive sive Adhe- Areal 0.30 Cal Descrip-Weight sive Density FSP V₅₀ tion Adhesive ID (gsm) (wt %) (psf) (fps) A1Polyamide 5.93 10.4 2.01 1873 A1 Polyamide 3.10 5.7 1.88 1984 C1Ethylene Vinyl 5.93 10.4 2.03 1957 Acetate Copolymer D1 Polyurethane15.25 22.9 2.02 1818 E1 Ethylene Acrylic 5.93 10.4 2.02 1832 AcidCopolymer B1 Polyolefin 5.93 10.4 2.01 1937 B1 Polyolefin 3.10 5.7 2.051878 F1 Polystyrene- 7.40 12.6 2.01 2057 Isoprene Copolymer F1Polystyrene- 5.70 10.0 2.07 2124 Isoprene Copolymer Dyneema Polystyrene-— — 1.99 2275 HB2 Isoprene Dyneema Polyurethane — — 2.00 2192 HB25

TABLE 3 Data Results for Ballistic-resistant panels of UHMWPE tapeformed with various adhesives at Molding Pressure 3,000 psi andBallistic Test Results: Adhe- Average Adhesive sive Adhe- Areal 0.30 CalDescrip- Weight sive Density FSP V₅₀ tion Adhesive ID (gsm) (wt %) (psf)(fps) A1 Polyamide 5.93 10.4 1.94 1915 C1 Ethylene Vinyl 5.93 10.4 1.961963 Acetate Copolymer B1 Polyolefin 5.93 10.4 1.96 2014 B1 Polyolefin3.10 5.7 2.02 1970 F1 Polystyrene- 7.40 12.6 2.03 2242 IsopreneCopolymer F1 Polystyrene- 5.70 10.0 2.02 2136 Isoprene Copolymer DyneemaPolystyrene- — — 2.00 2541 HB2 Isoprene Dyneema Polyurethane — — 2.002386 HB25

A summary of the data suggest that the 3000 psi ballistic-resistantpanels molded with adhesives A1, B1, and C1 rated slightly higher forballistic performance than did the 150 psi panels. Adhesives B1 and C1were essentially equal in performance. The V₅₀ results suggest that allof the test panels were acceptable for ballistic resistance of 0.30caliber fragment simulated projectiles.

Ballistic-resistant panels were then prepared to test the performance ofTensylon tape versus conventional high modulus fibers. Dyneema HB25cross-plied fibers embedded in resin, available from DSM Dyneema B.V.,Urmond, the Netherlands, were formed into a 2.0-psf panel. A panelformed of 100% HB25 as the high modulus component was used as a controlsample or baseline. A nominal 2.0-psf panels was also formed of 100%high modulus Tensylon tape. Various other combinations of Tensylon tapeand HB25 were formed into ballistic-resistant panels to test theballistic resistance of panels with various amounts of Tensylon tape inplace of the conventional high modulus component and to also testwhether the Tensylon tape was more effective in various configurations,such as 1) alternating sheets of Tensylon tape and conventional highmodulus component, 2) Tensylon tape as a strike-face at the front of theballistic-resistant panel, and 3) Tensylon tape as the backing materialwith conventional high modulus component forming the strike face, and 4)varying the ratio of Tensylon tape to conventional high moduluscomponent. Several of these variations were molded into panels at 150psi and 250° F. as shown in Table 4 below, and several molded intopanels at 150 psi and 210° F. as shown in Table 5. Theballistic-resistant panels were tested with 0.30 caliber FSP rounds andthe V₅₀ results recorded.

Table 4 includes, left to right in columns 1 to 7:1) the high moduluscomposition, 2) the baseline V₅₀ test result for panels formed of onehigh modulus component, 3) the V₅₀ test result for panels formed with aTensylon strike-face, 4) the V₅₀ test result for panels formed with HB25as the strike-face, 5) the calculated V₅₀, and 6) the delta V₅₀ which isthe difference between the calculated V₅₀ and the actual V₅₀ recorded incolumns 3, 4, or 5. The calculated V₅₀ is determined by the Rule ofMixtures wherein the property of a composite is proportional to thevolume fractions of the materials in the composite, thus the calculatedV₅₀ for a 50/50 ratio of Tensylon C and HB25 is V₅₀=0.5 (1650)+0.5(2250) or V₅₀ (calculated)=1950. The Tensylon C (Ten C) and Tensylon A(Ten A) were panels molded with different adhesives.

Thus, if the Delta V₅₀ is within plus or minus 50 fps, the Rule ofMixtures is a good predictor of the final V₅₀ value, and there is noeffect from the manner in which the separate high modulus components arecombined in the panel. Thus the V₅₀ for alternating layers of Tensylontape and HB25, which is represented by line 4 of the table, is predictedby the Rule of Mixtures. However, if the absolute value of the Delta V₅₀is significantly greater than 50 fps for several of the test panels, itimplies that the order in which the high modulus components are arrangedin the ballistic-resistant panel is statistically significant. Thus,where the Tensylon tape is placed with respect to front or back in theballistic-resistant panel has a significant effect on the ballisticperformance of the panel. A Delta V₅₀ that is greater than +50 fpsindicates a higher ballistic resistance result than expected by the Ruleof Mixtures and thus an advantageous configuration of high moduluscomponents within the panel. A Delta V₅₀ that is less than −50 fpsindicates a lower ballistic resistance result than expected by the Ruleof Mixtures and thus an undesirable configuration of high moduluscomponents within the panel.

Therefore, it can be concluded from the test results in Table 4 that thecompositions in rows 5 and 10 through 12 are advantageous for producinga panel with high ballistic resistance. Column 1 shows the high moduluscomposition of these panels are 25% Tensylon/50% HB25/25% Tensylon(panel 5), 25% Tensylon/75% HB25 (panels 10 and 11), and 50%Tensylon/50% HB25 (panel 12). Results therefore show that a strike-faceconsisting of high modulus UHMWPE Tensylon tape improves the performanceof ballistic-resistant panels. In the final ballistic-resistant panel,the adhesive was less than 20 weight percent of the total weight of thepanel.

TABLE 4 Test Results of 2.0 psf Ballistic-resistant panels at MoldingPressure 150 psi and 250° F. Temperature: Baseline Tensylon TensylonDelta High Modulus Ratio 0.30 cal. Front Back Calculated V₅₀ Component(%) V₅₀ (fps) V₅₀ (fps) V₅₀ (fps) V₅₀ (fps) (fps) HB25 100 2250 — — — —Tensylon C 100 1650 — — — — Tensylon A 100 1933 — — — — TenC/HB25 alt.*50/50 — 1965 — 1950 +15 TenC/HB25/TenC 25/50/25 — 2211 — 1950 +261HB25/TenC/HB25 25/50/25 — — 1989 1950 +39 HB25/TenA 50/50 — — 1933 2092−159 HB25/TenC 50/50 — — 1750 1950 −200 HB25/TenC 75/25 — — 1852 2101−249 TenC/HB25 25/75 — 2333 — 2101 +232 TenA/HB25 25/75 — 2255 — 2151+104 TenC/HB25 50/50 — 2217 — 1950 +267 TenC/HB25 alt.* — alternatinglayers of Tensylon C and HB25.

Table 5 includes ballistic test results for panels of variouscompositions of Tensylon UHMWPE tape and HB25 fibers molded at 150 psiand 210° F. The ballistic-resistant panels were tested with 0.30 caliberFSP rounds and the V₅₀ velocities recorded.

TABLE 5 Test Results of 2.0 psf Ballistic-resistant panels at MoldingPressure 150 psi and 210° F. Temperature: Baseline Tensylon TensylonHigh Modulus 0.30 cal. Front Back Calculated Delta V₅₀ Component Ratio(%) V₅₀ (fps) V₅₀ (fps) V₅₀ (fps) V₅₀ (fps) (fps) HB25 100 2154 — — — —Tensylon A 100 1986 — — — — HB25/TenA 50/50 — — 1909 2070 −161 TenA/HB2550/50 — 2289 — 2070 +219 TenA/HB25 25/75 — 2300 — 2112 +188

As reference to Table 5 shows, the ballistic resistance for the 2.0 psfpanels molded at 150 psi and 210° F. was improved significantly withTensylon UHMWPE tape used as the strike face of the panel. Theimprovement in ballistic resistance with the addition of Tensylon tapeas the strike face therefore occurred with panels molded at 250° F.(Table 4) as well as at 210° F. (Table 5).

Table 6 includes ballistic test results for 3.8 nominal psfballistic-resistant panels composed of Tensylon UHMWPE tape and aramidfabric molded with SURLYN® resin at 150 psi and 250° F. SURLYN® is anethylene/methacrylic acid copolymer available from DuPont Packaging andIndustrial Polymers of Wilmington, Del. The aramid fabric is producedcommercially by Barrday, Inc. under the trade name Barrday Style 1013.The aramid fabric was composed of 3,000 denier Kevlar® 29 in fabrics of14 oz/yd² weight. One ply of 1.5-mil CAF film (SURLYN® resin) was usedbetween each ply of Tensylon tape. (As a result of aramid fabric andTensylon tape weight variances, it was difficult to match arealdensities. The ballistic-resistant panels were tested with 0.30 caliberFSP rounds and the V₅₀ velocities recorded.

TABLE 6 Test Results of 3.3 psf Ballistic-resistant panels at MoldingPressure 150 psi and 250° F. Temperature: Baseline Tensylon TensylonHigh Modulus Ratio 0.30 cal. FSP Front Back Calculated Delta V₅₀Component (%) V₅₀ (fps) V₅₀ (fps) V₅₀ (fps) V₅₀ (fps) (fps) Aramid 1002491 — — — — Tens/Ara alt.* 50/50 2320 — — 2405  −85 Tens/Ara 50/50 —2632 — 2405 +227 Ara/Tens 50/50 — — 2275 2405 −130 Tens/Ara alt.* —alternating layers of Tensylon and Aramid.

As shown in Table 6, the test panel with a Tensylon tape strike face hadballistic resistance of 2632 fps, which was significantly higher thanthat predicted by the Rule of Mixtures.

Table 7 includes ballistic test results for 3.8 nominal psfballistic-resistant panels composed of Tensylon UHMWPE tape and HB25 andtested with an NIJ Level III M80 ball projectile (U.S. militarydesignation for 7.62 mm full metal jacketed bullet).

TABLE 7 Test Results - 3.8 psf Ballistic-resistant panels, M80 Ball: V₅₀Molding Areal Calculated M80 Delta High Modulus Ratio Pressure DensityM80 ball ball V₅₀ Component (%) (psi) (psf) V₅₀ (fps) (fps) (fps) HB25100 150 4.01 — 2965 — Tensylon 100 150 4.00 — 2107 — Tens/HB25 alt.*50/50 150 3.80 2565 2416 −149 Tensylon/HB25 50/50 150 3.85 2565 2880+315 Tensylon/HB25 25/75 150 3.85 2750 2897 +147 Tens/HB25 alt.* —alternating layers of Tensylon and HB25.

As shown in Table 7 for nominal 3.8 psf composite ballistic-resistantpanels, the Tensylon UHMWPE tape had a beneficial effect when placed asthe strike-face of the ballistic-resistant panel, including a V50velocity of 2880 fps for the ballistic-resistant panel in which theTensylon tape comprised the strike-face and 50% of the high moduluscomponent and a V50 velocity of 2897 fps for the ballistic-resistantpanel in which the Tensylon tape comprised the strike-face and 25% ofthe high modulus component.

Table 8 includes ballistic test results for a spall liner for simulatedarmor with facings of aluminum and High Hardness Steel (HHS) and variousbacking compositions including various weights of HB25 and variouscompositions including HB25 and Tensylon tape. All of the armor designsincluding Tensylon tape as a high modulus component had positive resultsfor rifle threat relative to the requirement.

TABLE 8 Ballistic Data Summary - Spall Liner: Rifle Frag.** ThreatThreat Total Relative Relative Armor Design AD to Rqmt.* to Rqmt. FacingBacking (psf) (fps) (fps) 1″ 6061 2.5 psf HB25 27.2 +232 fps Not testedAl/¼″ HHS 3.0 psf HB25 27.7 −42 Not tested 3.5 psf HB25 28.2 +419 Nottested 1.25 psf Ten/1.25 psf HB25 27.2 +152 Not tested 1.50 psf Ten/1.50psf HB25 27.7 +144 Not tested 1.75 psf Ten/1.75 psf HB25 28.2 +564 +10001.5″ 6061 1.30 psf HB25 33.1 +412 Not tested Al/¼″ HHS 1.25 psf Ten/1.25psf HB25 33.1 >+464 Not tested 1.60 psf Ten 33.4 +390 +1639*Rqmt.—Requirement. **Frag.—Fragmentation

Table 9 includes ballistic test results for a simulated spall linerincluding the following various configurations: 1) a baselineconfiguration of ¼″ Ultra High Hard Steel (UHHS) and 1.1 psf of KEVLAR®Reinforced Plastic (KRP), 2) baseline plus 25-mm of HB25 spaced 25-mmbehind the KRP, 3) baseline plus 25-mm of high modulus componentscomprised of 25% Tensylon and 75% HB25 spaced 25-mm behind the KRP, and4) baseline plus 25-mm of high modulus components comprised of 50%Tensylon and 50% HB25 spaced 25-mm behind the KRP. Test results includedthe spall cone angle measured at layers 1 and 3 and the average numberof fragments that penetrated at layers 1 and 3. The spall cone angle andaverage number of fragments through for a spall liner including 25% and50% Tensylon tape were similar to those obtained for a spall liner of100% HB25.

TABLE 9 Ballistic Data Summary - Simulated Spall Liner, 20 mm FSP: SpallCone Average # of Angle (degrees) Fragments Through Material Layer 1Layer 3 Layer 1 Layer 3 Baseline Configuration: 66.44 61.70 214.5 35.0¼″ UHHS + 1.1 psf KRP Baseline with: 51.12 35.04 88.50 11.0 25-mm HB25spaced 25-mm behind KRP Baseline with: 56.46 36.75 89.50 10.5 25-mm 25%Tens/75% HB25 spaced 25-mm behind KRP Baseline with: 52.58 32.57 103.09.0 25-mm 50% Tens/50% HB25 spaced 25-mm behind KRP

In another embodiment, ballistic-resistant panels were constructed usingTensylon tape as the high modulus component to determine the effect ofmolding pressure and temperature on ballistic resistance. Table 10includes ballistic test results for 2.0 psf panels comprised ofcross-plied layers of 1.62-inch width Tensylon UHMWPE tape, with a firstseries of panels molded at 150 psi and at various temperatures and asecond series of panels molded at 500 psi and at various temperatures.The cross-plied layers of Tensylon UHMWPE tape were interleaved with alow density polyolefin scrim (Spunfab PO4605) and pressed and bonded atthe various pressures and temperatures recorded in the table. The lastentry in Table 10, Tensylon*, was comprised of layers of 1.62-inchTensylon tape woven into a fabric using a basket weave with the weftarranged at 90° with respect to the warp. The woven layers were pressedwith an 18-micron low density polyethylene film to form a 2.2 psfballistic-resistant panel. The ballistic-resistant panels were testedwith 0.30 caliber FSP rounds per MIL-P-46593A and the average V₅₀velocities recorded.

TABLE 10 Test Results of 2.0 psf Ballistic-resistant panels at MoldingPressures 150 psi and 500 psi and at various Temperatures: MoldingAverage High Modulus Pressure Temperature V₅₀ Component (psi) (degreesF.) (fps) Tensylon B1 150 200 1601 Tensylon B1 150 210 1702 Tensylon B1150 220 1630 Tensylon B1 150 230 1689 Tensylon B1 150 240 1611 TensylonB1 150 250 1634 Tensylon B1 150 260 1577 Tensylon B1 150 270 1543Tensylon B1 150 280 1551 Tensylon B1 500 180 1790 Tensylon B1 500 1901717 Tensylon B1 500 200 1692 Tensylon B1 500 210 1647 Tensylon B1 500220 1588 Tensylon B1 500 230 1593 Tensylon B1 500 240 1566 Tensylon B1500 250 1649 Tensylon B1 500 260 1703 Tensylon* 500 250 1826 *2.2 psfpanel formed of Tensylon 0/90 weave with 1″ tape.

As shown in FIG. 6, the resultant average V₅₀ values for the Tensylon B1panels of Table 10 were plotted versus temperature and a regression linefitted each series of data points. The ballistic resistance of thepanels generally increased as the molding temperature was decreased.

Although the embodiments of ballistic-resistant panels describe abovewere prepared at specific parameters, other variations of processingconditions are possible without departing from the scope of theinvention. For example, although the Tensylon UHMWPE tape in adjacentlayers of the ballistic-resistant panel were oriented at 0° and 90°respectively, other orientations are possible, such as 0° and 45° inadjacent layers, or 0°, 45°, and 90° for each three successive layers.Preferably the direction of orientation of the tape in each of theinterleaved layers of non-fibrous ultra high molecular weightpolyethylene tape is at an angle of at least 30 degrees with respect tothe direction of orientation of the tape in an adjacent layer. Althoughthe specific molding temperatures tested herein were between 180 and280° F., it is believed that molding temperatures between 150° F. and300° F. are acceptable for forming a ballistic-resistant panel accordingto the present invention. Although specific molding pressures of 150,500, and 3000 psi were tested, it is believed that molding pressuresbetween 100 and 4000 psi are acceptable for forming ballistic-resistantpanels according to the present invention.

Although in one embodiment herein the Tensylon tape was woven into afabric using a basket weave, it is within the scope of the presentinvention to form the Tensylon tape into fabric using any fabric weave,such as plain weave, twill weave, satin weave, and the like.

Having thus described the invention with reference to a preferredembodiment, it is to be understood that the invention is not so limitedby the description herein but is defined as follows by the appendedclaims.

1. A ballistic-resistant panel comprising: a compressed stack ofinterleaved layers of high modulus material wherein said high modulusmaterial includes a modulus greater than 1,000 grams per denier; a firstportion of said interleaved layers of high modulus material including aplurality of interleaved layers consisting of non-fibrous ultra highmolecular weight polyethylene (UHMWPE) tape; a second portion of saidinterleaved layers of high modulus material including a plurality ofinterleaved layers consisting of cross-plied fibers embedded in resin;and an adhesive on each of said interleaved layers of said non-fibrousultra high molecular weight polyethylene tape.
 2. Theballistic-resistant panel of claim 1 wherein each of said layers ofnon-fibrous ultra high molecular weight polyethylene tape includes aplurality of tape strips; said tape strips including a width of at least1.0 inch; said tape strips include edges; and said tape strips are fusedtogether in a butt joint or overlap joint at said edges or woven into afabric.
 3. The ballistic-resistant panel of claim 1 wherein saidnon-fibrous ultra high molecular weight polyethylene tape includes aviscosity-average molecular weight of at least 2,000,000; a thickness ofbetween 0.0015 and 0.004 inch; and a modulus of greater than 1400 gramsper denier.
 4. The ballistic-resistant panel of claim 1 wherein saidtape in each of said interleaved layers of non-fibrous ultra highmolecular weight polyethylene tape is unidirectional; and the directionof orientation of said tape in each of said interleaved layers ofnon-fibrous ultra high molecular weight polyethylene tape is at an angleof at least 30 degrees with respect to the direction of orientation ofsaid tape in an adjacent layer of said tape.
 5. The ballistic-resistantpanel of claim 1 wherein said compressed stack of interleaved layers ofhigh modulus material are compressed and bonded together at a pressureof between 100 and 4,000 psi; and a temperature of between 150 and 300degrees F.
 6. (canceled)
 7. The ballistic-resistant panel of claim 1wherein said adhesive on each of said interleaved layers of saidnon-fibrous ultra high molecular weight polyethylene tape is selectedfrom the group consisting of polyamide, polyolefin, ethylenevinylacetate copolymer, polyurethane, ethylene acrylic acid copolymer,polystryrene-isoprene copolymer, or ethylene/methacrylic acid copolymer.8. The ballistic-resistant panel of claim 1 wherein said adhesivecomprises between 5.7 and 10.4 weight percent of the total weight ofsaid panel.
 9. The ballistic-resistant panel of claim 2 wherein saidnon-fibrous UHMWPE tape strips are formed from stretching partiallyoriented UHMWPE tape to a total draw ratio of 100:1 or greater whereinthe draw ratio is defined as the length after stretching divided by thelength before stretching; said tape strips include a width to thicknessratio of at least 400:1; and said tape strips include a denier of 6,000or greater.
 10. The ballistic-resistant panel of claim 1 wherein saidadhesive includes a scrim or film of adhesive on each of saidinterleaved layers of non-fibrous UHMWPE tape.
 11. Theballistic-resistant panel of claim 1 wherein each of said interleavedlayers of said non-fibrous UHMWPE tape includes two sides; and saidadhesive is in the form of a liquid dispersion applied to one of saidnon-fibrous UHMWPE tape.
 12. The ballistic-resistant panel of claim 1wherein said first portion of said interleaved layers form thestrike-face of said ballistic-resistant panel. 13-16. (canceled)
 17. Aballistic-resistant panel comprising: a plurality of interleaved layersconsisting of non-fibrous ultra high molecular weight polyethylene tape;each of said layers of non-fibrous ultra high molecular weightpolyethylene tape including a plurality of monolithic tape strips joinedtogether in a sheet structure including joints between adjoining stripswherein said joints include an intermingling of molecules between saidmolecules of said adjoining strips and a higher strength in said jointsthan in said adjoining strips and each of said tape strips including amodulus of greater than 1400 grams per denier; said plurality of tapestrips in each of said layers including a first portion of tape stripsoriented at a first angle and a second portion of tape strips orientedat substantially 90 degrees with respect to said first angle; and saidplurality of interleaved layers of non-fibrous ultra high molecularweight polyethylene tape bonded together by heat and pressure.
 18. Theballistic-resistant panel of claim 17 wherein said heat of bonding is atleast 150 degrees F. and said pressure of bonding is at least 150 psi.19. The ballistic-resistant panel of claim 17 wherein said first portionof tape strips in said layer includes a first ply of tape stripsarranged side to side in a butt joint and bonded together by heat andpressure; said second portion of tape strips in said layer includes asecond ply of tape strips arranged side to side in a butt joint andbonded together by heat and pressure; and said first portion of tapestrips and said second portion of tape strips are bonded together toform a cross-plied layer. 20-27. (canceled)
 28. A ballistic-resistantarticle comprising a metallic strike face and a plurality of interleavedlayers of polymeric material stacked against the strike face, theplurality of interleaved layers consisting of a multilayer sheet offirst and second layers, wherein at least some of the first layersconsist of drawn polymeric fibers and wherein at least some of thesecond layers consist of drawn polymeric tapes.
 29. (canceled)